Today, silver screen printing is the technology of choice for the realization of the top grid electrode in heterojunction silicon solar cells. The difficulty of lowering resistivity and thinning the metal line in silver screen printing prevents from achieving high efficiency and low cost. By replacing silver with copper, many problems seem to disappear.
In the presented silver-free approach, the screen-printed silver is replaced by electroplated copper. Formation of top grid electrode with copper-electroplating in hetero-junction silicon solar cells is the world first result. This solution not only overcomes the disadvantages of the silver screen printing, but provides advantages such as enabling higher efficiencies and reducing fabrication costs.
These results were obtained in a bilateral collaboration between Kaneka Corporation and imec in Leuven (Belgium). Kaneka’s Photovoltaics European Laboratory is located at the imec campus in Leuven, giving access to imec’s PV infrastructure and enabling close interaction between researchers. The collaboration between Kaneka and imec comprises the improvement of Kaneka’s thin-film solar cells and the development of next-generation heterojunction cells.